Crack Propagation in Additive Manufactured Materials and Structures

Riemer, Andre; Richard, Hans Albert

doi:10.1016/j.prostr.2016.06.157

Cited by 37 publications

(20 citation statements)

References 7 publications

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“…Riemer and Richard investigated the effects of build‐up rate (cm 3 /h) on the crack growth behaviour of SLM 316L steel. Crack growth testing showed a huge decrease in threshold values, Δ K th , when increasing the build‐up rate: 3.8 MPa m 1/2 for 30‐μm layer thickness with 175‐W laser power to 2.4 MPa m 1/2 for 100‐μm layer thickness with 950‐W laser power.…”

Section: Review Of Previous Studies On Crack Growth In 316l Produced mentioning

confidence: 99%

Study of the effect of heat treatment on fatigue crack growth behaviour of 316L stainless steel produced by selective laser melting

Fergani

Wold²,

Berto³

et al. 2017

Fatigue Fract Eng Mat Struct

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This study is focused on stainless steel type 316L produced by selective laser melting (SLM). This steel is very resistant to corrosion in acidic environments and has extremely good strength properties at elevated temperatures. It is also characterized by a very good weldability. These properties allow for various applications of 316L in different fields. The widespread application of 316L opens up various possibilities for production of parts using SLM. Therefore, it is important to characterize the fatigue crack growth behaviour. In the present paper, the crack growth behaviour of SLM 316L stainless steel has been investigated in its as‐built condition and in different heat treatment conditions. The effect of build orientation on the crack growth path is also studied by performing fatigue crack growth tests on compact tension specimens built at 0° and 45° orientations relative to the build direction. A heat treatment above the recrystallization temperature followed by quenching is shown to create compressive residual stresses that improve the resistance against crack propagation considerably. The 45° build orientation shows crack propagation at an angle to the initial notch plane, which reveals that anisotropy still persists after heat treatment.

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Section: Review Of Previous Studies On Crack Growth In 316l Produced mentioning

confidence: 99%

Study of the effect of heat treatment on fatigue crack growth behaviour of 316L stainless steel produced by selective laser melting

Fergani

Wold²,

Berto³

et al. 2017

Fatigue Fract Eng Mat Struct

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“…In general, hotter build process results in more ductile microstructure than that of SLM, which is richer in martensite, strong but brittle . Both heat treatment and HIP processes can significantly improve these properties …”

Section: Introductionmentioning

confidence: 99%

“…17,19 In both studies, the authors attributed the inferior fracture toughness in the as-built form to the fine and brittle acicular martensitic structure caused by rapid solidification of the material. In terms of the FCGR, the EBM Ti64 exhibited slower crack growth rates in the Paris law region than that in the wrought condition, in both orientations, 16 whereas FCGR in the SLM Ti64 in the as-built condition was faster in the lower ΔK region (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) and slower in the higher ΔK region (30-80 MPa√m) at load ratio of 0.1. 17 Similar trend was found by another study, 19 in which SLM Ti64 had slower FCGR than the wrought alloy in all three orientations at load ratio 0.1.…”

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confidence: 99%

“…17,19 Both heat treatment and HIP processes can significantly improve these properties. [21][22][23] So far, there is no published work on the fracture toughness and fatigue crack growth properties in the wire-fed AM Ti64. From a geometrical point of view, WAAM® can produce deposits of varying thickness by changing process parameters, such as the current, wire feed speed (WFS) or travel speed (TS).…”

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confidence: 99%

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Fracture toughness and fatigue crack growth rate properties in wire + arc additive manufactured Ti‐6Al‐4V

Zhang

Martina

Ding

et al. 2016

Fatigue Fract Eng Mat Struct

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A B S T R A C T This paper presents an experimental investigation of the fracture and fatigue crack growth properties of Ti-6Al-4V produced by the Wire + Arc Additive Manufacture (WAAM®) process. First, fracture toughness was measured for two different orientations with respect to the build direction; the effect of wire oxygen content and build strategy were also evaluated in the light of microstructure examination. Second, fatigue crack growth rates were measured for fully additive manufactured samples, as well as for samples containing an interface between WAAM® and wrought materials. The latter category covers five different scenarios of crack location and orientation with respect to the interface. Fatigue crack growth rates are compared with that of the wrought or WAAM® alone conditions. Crack growth trajectory of these tests is discussed in relation to the microstructure characteristics.Keywords fatigue crack growth; fracture toughness; microstructure; titanium; wire + arc additive manufacture. N O M E N C L A T U R Ea = Crack length B = Compact tension specimen thickness K IC = Plane-strain fracture toughness K Q = Conditional fracture toughness value P max = Applied load at fracture P Q = Conditional load value at fracture determined by ASTM Standard W = Compact tension specimen width σ ys = Material yield strength under tension load I N T R O D U C T I O NTitanium alloy Ti-6Al-4V (Ti64) has been used in the aerospace and other industries owing to its high specific strength, excellent resistance to fatigue and corrosion, and good performance at elevated temperature. With the increasing use of carbon fibre polymer composites in the airframes, titanium will be increasingly used because of its good compatibility with this material. However, titanium alloys are extremely expensive and very difficult to machine, if compared with other aerospace alloys such as aluminium. Therefore, using the Additive Manufacture (AM) technology to build titanium parts has become very attractive owing to the significant reduction in material waste, machining and tooling cost, manufacturing energy and time to market. Conventional powder bed AM also makes it possible to easily produce complicated parts. However, the cost of material powder is usually particularly high, which affects the overall cost of the process. This drawback is counterbalanced by the reduced material waste. Studies have shown that AM can be an economically and environmentally superior option to the traditional methods of machining from cast or forged billets for production in small batches.

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“…One area of ongoing investigation concerns the modification of the mechanical properties of additively manufactured elements. Both the layer-by-layer characteristic of the process and the use of process parameters allow for the control of element properties through a variety of methods, including process parameter modification [6,7], heat treatment after selective laser melting (SLM) processing [8,9], element topology [11], and surface treatment [12] after SLM processing [11,12]. A proper surface parameters have a significant influence on elements properties which was deeply investigated by Macek et al in their work [15].…”

Section: Introductionmentioning

confidence: 99%

Effect of Process Parameter Modification and Hot Isostatic Pressing on the Mechanical Properties of Selectively Laser-Melted 316L Steel

Kluczyński¹,

Śnieżek²,

Grzelak³

et al. 2020

Preprint

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Industries that rely on additive manufacturing of metallic elements, especially biomedical companies, require material science-based knowledge of how process parameters and methods affect element properties, but such phenomena are incompletely understood. In this study, we investigated the influence of selective laser melting (SLM) process parameters and additional heat treatment on mechanical properties. The research included structural analysis of residual stress, microstructure, and scleronomic hardness in low-depth measurements. Tensile tests with element deformation analysis using digital image correlation (DIC) were performed as well. Experiment results showed it was possible to observe the porosity growth mechanism and its influence on material strength. Elements manufactured with 20% lower energy density had almost half the elongation, which was directly connected with porosity growth during energy density reduction. Hot isostatic pressing (HIP) treatment allowed for a significant reduction of porosity and helped achieve properties similar to elements manufactured using different levels of energy density.

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Crack Propagation in Additive Manufactured Materials and Structures

Cited by 37 publications

References 7 publications

Study of the effect of heat treatment on fatigue crack growth behaviour of 316L stainless steel produced by selective laser melting

Study of the effect of heat treatment on fatigue crack growth behaviour of 316L stainless steel produced by selective laser melting

Fracture toughness and fatigue crack growth rate properties in wire + arc additive manufactured Ti‐6Al‐4V

Effect of Process Parameter Modification and Hot Isostatic Pressing on the Mechanical Properties of Selectively Laser-Melted 316L Steel

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